Rebirth is something all beings in this world undergo; their souls constantly go through refinement and recycling, returning to the physical world to be utilized once again. This is one of the universal laws: everything in the universe eventually returns to it. This applies to all beings, even those who claim to be immortal or primordial entities.
It was not difficult for a soul to reincarnate while retaining its form, memories, and personality. In fact, it was more common than it seemed. All of this derived from two circumstances: the strength of the soul and its impact on the universe.
